Field of the Invention
The present invention is directed to a device for repairing or reinforcing a member such as a tubular member, a pipeline, or structural support, which device comprises fabric and nanomaterial toughening and strengthening material and a polymer matrix. This invention also relates generally to the field of nanoparticles, and more specifically, to methods for dispersing nanoparticles into a matrix or compound.
Background/Description of Related Art
A wide variety of devices, apparatuses, systems and methods for repairing or reinforcing members such as pipe, pipelines, and structural members are known, including, but not limited to, the disclosures in U.S. Pat. Nos. 4,700,752; 5,348,801; 5,445,848; 5,632,307; 4,676,276; 6,276,401; 6,774,066; 7,387,138; 7,426,942; 7,367,362; 7,500,494; and 7,523,764—all incorporated fully herein for all purposes.
Structural members can be degraded, i.e. physically damaged or deteriorated due to cyclic loading fatigue enhanced by corrosion, erosion, temperature fluctuations, natural causes, third party causes, and time. Degraded members often require repair and/or reinforcement to preserve and/or restore their integrity and extend their useful life. The problems resulting from damage and deterioration affect piping systems which are subject to deterioration due to several factors, including sulfate reducing bacteria, galvanic action, and third party damage. The problem is not limited to piping systems. It also affects other structures such as piling, concrete columns, petroleum storage tanks, etc. which are subject to deterioration and damage.
Older methods of repairing damaged pipelines comprise the replacement of the damaged or defective pipe section with new pipe or the installation of a metal sleeve over the damaged or defective area. Depressurizing the pipe or putting the pipe out of service while the pipe replacement is performed is often required for these known pipe repair methods. This procedure can become costly and inconvenient for the pipeline owner as well as the general public.
Advances in composite materials and methods in the past two decades have introduced composites as a more widely accepted repair method for piping and infrastructure rehabilitation. Composites have offered owners of pipelines a cost-effective alternative to the disruption of service caused by pipe replacement or steel sleeves because composite repairs can be applied to the damaged areas while the pipeline is still in operation.
Known pipe repair and reinforcement systems include a fabric impregnated with a moisture-curing polyurethane polymer system or a fabric impregnated with a resin polymer in the field during installation of the product or a cured pre-form that is bonded with an adhesive as it is wrapped around a member. These products provide reasonable performance and service life. However, there is a need for improved performance especially in the area of extended fatigue/service life.
Permanence of a Fiber Reinforced Polymer, “FRP” composite repair is a requirement for pipeline repair methods under current DOT regulations (49 CFR §§192, 195; incorporated fully herein). The question of permanence of some FRP composite repairs has become of great concern to pipeline owners due to delaminations due to fatigue of some composite systems.
Consequently, these failed FRP's have provided questionable permanent repairs. DOT has ruled that FRP repairs are temporary unless the pipe is repaired by a method that reliable engineering tests and analyses show permanently restores the serviceability of the pipe.
With the discovery of nanoparticles, it has been scientifically shown under laboratory conditions that the physical properties of a matrix and/or composite material such as tensile strength, tensile modulus, thermal and electrical conductivity, toughness, durability, etc., are enhanced with the incorporation of nanoparticles such as but not limited to nanotubes, graphene, nanofibers, bucky balls, nano clays, etc. (collectively “nanoparticles”). For example, it is known in the art that in the laboratory, epoxies have been impregnated with nanoparticles to form a hardened material. A matrix, in this sense, is generally understood to be defined as a pre-cured material, liquid or molten state that may include for example, but is not limited to, polyester resin, vinyl ester resin, epoxy resin, polyethylene, polypropylene, nylon, rubber, and the like. The composite material may generally be defined as any material that incorporates a fiber or aggregate that increases the resultant material's “load carrying” capability.
Although these nanoparticles enhance the physical material properties of a matrix and/or composite material, there are two challenges that remain in converting laboratory research results into viable full scale manufacturing. These challenges center about ensuring the proper and uniform placement of these nanoparticles within the material to be enhanced. The initial difficulty is related to the large aspect ratio (length versus diameter) that causes difficulty in separating the nanoparticles from themselves. This is analogous to separating wet spaghetti noodles that are balled up.
The second, but most critical challenge of integrating nanoparticles, is that once the nanoparticles are separated, it is important to ensure the even dispersement or placement of the nanoparticles into the matrix. Improperly placed nanoparticles, or poorly dispersed nanoparticles, can result in the formation of nano-cluster pockets which create areas of embrittlement resulting in premature failure of the matrix instead of enhancement of the matrix. This specific challenge is probably the one single largest problem in advancing nano-technology into the arena of actual products. Advancing from dispersion of nanoparticles into a matrix at the laboratory bench scale to a commercial scale has proven a difficult task, and current methods are inadequate.
Berger (2008) describes that owing to the fact that carbon nanotubes (CNTs) are insoluble in most solvents, and other liquids, such as polymer resins and water, it becomes difficult to evenly disperse CNTs into a liquid matrix such as epoxies and other polymers. This in turn complicates efforts to use the outstanding physical properties of CNTs in the manufacture of nanocomposite materials. It also complicates efforts for preparation of uniform mixtures of CNTs with different organic, inorganic and polymeric materials for use in other practical nanotechnology applications.
Current methods for separating nanoparticles involve suspension of the nanoparticles into a carrier such as a solvent through vibration by a sonication device, then introducing the suspended nanoparticles to the matrix and dispersing the suspension throughout the matrix by a mixing process that utilizes high shear mixing blades for some length on time. While this process does work, it is unrealistic for manufacturing because, for example, the abovementioned process requires approximately 7 hours of time to process 300 ml of epoxy matrix. Another method involves a three roll mixer that kneads and rolls the material around, but this method is inadequate because it is extremely difficult to achieve any predictability of uniform nanomaterial dispersion with changes in mix batch sizes. Additionally, while a hardened, nanoparticle-reinforced epoxy has been produced at the lab bench scale, there exists a need to provide for in-situ repairs using such nanoparticle-reinforced materials so that such reinforced materials may be applied to the repair surface prior to hardening.
As such, there exists a great need to improve the methods of dispersing nanoparticles into a matrix and/or compound at a commercial level and the present invention provides such methods. Therefore, the present disclosure is directed to methods for evenly dispersing nanoparticles into a matrix or compound for the enhancement of physical properties of the matrix which may be used as a stand-alone product or enhance composite material properties when integrated with load-carrying fibers or aggregate. These methods enable the optimization of benefits derived from the addition of nanoparticles by the uniform placement of the particles within the matrix medium.